1. Field Of The Invention
The invention relates to propulsion systems for accelerating charged particles to generate propulsive force particularly adapted for use at high altitudes. More particularly the invention pertains to an ion engine having a cathode ion thruster or emitter for ionizing an ambient atmospheric gas in combination with an electrically insulative housing and a ring-shaped anode in which ions are accelerated and propelled through the ion engine to generate thrust from an ambient atmospheric gas. As used herein the term ambient atmospheric gas refers to an ionizable gas present in the troposphere, stratosphere and ionosphere that serves as fuel in the novel ion engine.
The novel ion engine is designed to run continuously at high altitudes and without maintenance for years without any fuel other than ambient atmospheric gas and a power source which preferably includes at least one renewable component such as solar energy. The novel ion engine not only does not pollute the earth's atmosphere but is designed to produce ozone in stratospheric operations to assist in repairing the hole in the ozone layer of the earth's upper atmosphere. The novel ion engine is designed to produce low thrust and operate at low velocities which as used herein means a thrust sufficient to maintain an airship in a geostationary position in the stratosphere.
The novel ion engine ionizes only a portion of the ambient atmospheric gas which ions are accelerated through an electric field from the cathode to the anode at which point ions bombard and collide with the remaining portion of ambient atmospheric gas to create propulsion during the lifetime of the ions existing between the cathode and anode. The cathode is charged to a potential of from about -18 to -110 kilovolts (kv) and possibly less in high altitude applications.
The novel ion engine may include accessory components such as tapered nacelles, compressors or other components for increasing the density of ambient atmospheric gas supplied to the novel ion engine and optionally include pre-ionizers, multiple stages and other means for increasing the ionization of the ambient atmospheric gas before it is introduced into the novel ion engine. The novel ion engine is designed for operation at stratospheric heights such as for example to maintain a geostationary position for a platform used for telecommunications applications, and provide propulsion in atmospheric conditions at high altitudes which means altitudes in the stratosphere 7 miles to 30 miles (11 to 31 kilometers (km)) and ionosphere 30 miles to 300 miles (11-500 km) above the earth's surface.
2. Description Of Related Prior Art
The prior art has long investigated propulsion systems which have few moving parts and utilize abundant natural resources as fuel while being environmentally safe. This is particularly true in high atmosphere and space exploration where engines must be reliable since defects and failure of moving parts make repair or replacement difficult and expensive. Furthermore high altitude and space applications provide limited natural resources for use as fuel.
The prior art has investigated various forms of rocket engines and ion engines for high altitude and space applications. These rocket engines and ion engines of the prior art use principles of ionization but do so in a different way than the present invention. Such prior art engines generally operate at high temperatures and attempt to either burn or ionize the highest possible percentage of the propellant since the propellant fuel must be carried with the airborne or space borne vehicle and cannot be wasted. Further such ion engines require high levels of power and utilize such exotic types of propellants as Argon, Cesium, Mercury, Xenon and others. The ion engine of the invention differs from such engines by not attempting to ionize all the available propellant and in not having to carry propellant in the attendant vehicle since the ion engine of the invention utilizes ambient atmospheric gas as the propellant.
The prior art has also proposed various forms of electrostatic, ion and corona-type devices for propulsion. The devices have employed various forms of grids, rings, wires and plates for the anode or the cathode which have required large amounts of electrical power and have produced large amounts of pollution by-products. Except for applications in outer space such devices are for the most part not practical due to their size, weight and power requirements. Such devices furthermore have not sought to focus or direct ionization on a selected portion of the air upon which they have sought to utilize as fuel for propulsion. The prior art devices also have not focused on the types of collisions of particles, their spacial relationship and the nature of the collisions that occur that are necessary for propulsion or the form of plasma that exists between the electrodes during the brief period the ions exist in the plasma before they are destroyed. The novel ion engine in contrast to the prior art utilizes a particular relationship between the cathode and anode as well as the formation of a particular type of plasma and the collisions that occur in that plasma to provide propulsion.
The novel ion engine of the invention is designed for use in the upper atmosphere to provide low velocity and low thrust to maintain a geostationary position for platforms used for telecommunications. Such applications require low maintenance, possible continuous operation, a renewable energy source and an abundant source of fuel or propellant. These requirements are provided by the novel ion engine which utilizes ambient atmospheric gas as a propellant, can utilize solar cells as a renewable power source and has virtually no moving parts that could wear out or require expensive repair or maintenance. The novel engine of the invention not only can meet these objectives but it is also environmentally compatible by producing ozone which is needed to repair the hole in the ozone layer and protect the earth from environmental damage.
The most relevant known patented prior art is Coleman, et al. U.S. Pat. No. 3,071,705 which creates propulsion by an "electric wind" resulting from the application of a high voltage positive charge to an anode having a toroid connected to an ionization head. In FIG. 3 toroid ionization head anode is placed in axial alignment with a cathode target having a metal ring connected to a target with the flow of air and corona discharge moving from the anode to the cathode.
The ion engines constructed in accordance with the invention are different in design and function from the Coleman, et al. '705 prior art engine. In contrast to Coleman, et al. '705 the novel ion engine has the flow of air and corona discharge move the opposite direction, namely from the cathode to the anode. In addition the novel engine does not employ a ring and toroid combination but instead a tapered cylindrical cathode ion thruster and a ring-shaped anode. The large cylinder and toroid anode electrode of Coleman, et al. '705 with a plurality of needle points 19 is different than the single sharply tapered or needle pointed cathode of the novel ion engine of the invention. This difference in design and construction not only results in differences in the shape and focus of flow patterns but also differences in the constituents of the "electric wind" or plasma created and its propulsive effect upon the other constituents of the electric wind and their collisions with neutral gas molecules.
Lindenblad U.S. Pat. No. 2,765,975 discloses an ionic wind generating duct to provide propulsion by employing a series of ion producing ion brooms connected to a high voltage source of either polarity. The ion brooms are disposed in a pipe or duct with alternating conductive and insulating sleeves which terminate in positive and negative voltage sources. The novel ion engine of the invention does not employ ion brooms but instead a focused and directed beam of ionic plasma directed from a cathode ion thruster directly at a ring-shaped anode.
More recent prior art pertaining to the construction and design of ion engines has been directed toward providing more efficient and exotic grids and screens to serve as electrodes or the utilization of more exotic forms of ion fuel than air. Examples of more recent prior art ion engines include Seidl U.S. Pat. No. 4,783,595 and Challoner, et al. U.S. Pat. No. 4,825,646 which proposes the use of the inert gas Xenon instead of prior art Mercury as a propellant for ion engines. Such exotic ion engines which have employed Cesium, Mercury and other exotic propellants have generally been employed in applications in outer space applications due to their cost and complexity. Recent prior art pertaining to grid and screen construction includes Garner U.S. Pat. No. 5,465,063 which pertains to a woven carbon fiber in a matrix of carbon and Banks U.S. Pat. No. 4,011,719 which pertains to a woven mesh screen of stainless steel wire cloth sputter coated with tantalum which serves as an anode for ion thrusters. These ion engines and ion engine components are different than the present novel ion engine since they do not use ambient atmospheric gaseous fuel.
The novel ion engine in contrast to the prior art utilizes a cylindrical finely tapered cathode ion thruster and a ring-shaped anode along with means for adjusting the distance between the cathode ion thruster and the ring-shaped anode. The novel ion engine in contrast to the prior art is non-polluting and produces ozone which at stratospheric levels should help alleviate past damage to the ozone layer due to fluorocarbon damage. The novel ion engine unlike the prior art ionizes a selected portion of the ambient atmospheric gas and controls the nature and types of collisions between the ions propelled from the ion thruster and the remaining portion of the ambient gas during the short duration of the life of the ion between the cathode ion thruster and the anode to provide thrust. The novel engines of the invention utilize these principles alone or together with pre-ionizers, multi-staged engines, compressors and other systems for increasing either the density of the ambient atmospheric gas or the efficiency of the process of ionization.